528 lines
13 KiB
C
528 lines
13 KiB
C
/* $NetBSD$ */
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/*
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* Copyright (C) 2002-2003 by Darren Reed
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*
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* Simple PPTP transparent proxy for in-kernel use. For use with the NAT
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* code.
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*
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* Id: ip_pptp_pxy.c,v 2.10.2.9 2005/03/16 18:17:34 darrenr Exp
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*
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*/
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#define IPF_PPTP_PROXY
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typedef struct pptp_hdr {
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u_short pptph_len;
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u_short pptph_type;
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u_32_t pptph_cookie;
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} pptp_hdr_t;
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#define PPTP_MSGTYPE_CTL 1
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#define PPTP_MTCTL_STARTREQ 1
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#define PPTP_MTCTL_STARTREP 2
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#define PPTP_MTCTL_STOPREQ 3
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#define PPTP_MTCTL_STOPREP 4
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#define PPTP_MTCTL_ECHOREQ 5
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#define PPTP_MTCTL_ECHOREP 6
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#define PPTP_MTCTL_OUTREQ 7
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#define PPTP_MTCTL_OUTREP 8
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#define PPTP_MTCTL_INREQ 9
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#define PPTP_MTCTL_INREP 10
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#define PPTP_MTCTL_INCONNECT 11
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#define PPTP_MTCTL_CLEAR 12
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#define PPTP_MTCTL_DISCONNECT 13
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#define PPTP_MTCTL_WANERROR 14
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#define PPTP_MTCTL_LINKINFO 15
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int ippr_pptp_init __P((void));
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void ippr_pptp_fini __P((void));
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int ippr_pptp_new __P((fr_info_t *, ap_session_t *, nat_t *));
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void ippr_pptp_del __P((ap_session_t *));
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int ippr_pptp_inout __P((fr_info_t *, ap_session_t *, nat_t *));
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void ippr_pptp_donatstate __P((fr_info_t *, nat_t *, pptp_pxy_t *));
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int ippr_pptp_message __P((fr_info_t *, nat_t *, pptp_pxy_t *, pptp_side_t *));
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int ippr_pptp_nextmessage __P((fr_info_t *, nat_t *, pptp_pxy_t *, int));
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int ippr_pptp_mctl __P((fr_info_t *, nat_t *, pptp_pxy_t *, pptp_side_t *));
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static frentry_t pptpfr;
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int pptp_proxy_init = 0;
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int ippr_pptp_debug = 0;
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int ippr_pptp_gretimeout = IPF_TTLVAL(120); /* 2 minutes */
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/*
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* PPTP application proxy initialization.
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*/
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int ippr_pptp_init()
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{
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bzero((char *)&pptpfr, sizeof(pptpfr));
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pptpfr.fr_ref = 1;
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pptpfr.fr_age[0] = ippr_pptp_gretimeout;
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pptpfr.fr_age[1] = ippr_pptp_gretimeout;
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pptpfr.fr_flags = FR_OUTQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
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MUTEX_INIT(&pptpfr.fr_lock, "PPTP proxy rule lock");
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pptp_proxy_init = 1;
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return 0;
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}
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void ippr_pptp_fini()
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{
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if (pptp_proxy_init == 1) {
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MUTEX_DESTROY(&pptpfr.fr_lock);
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pptp_proxy_init = 0;
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}
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}
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/*
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* Setup for a new PPTP proxy.
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*/
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int ippr_pptp_new(fin, aps, nat)
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fr_info_t *fin;
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ap_session_t *aps;
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nat_t *nat;
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{
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pptp_pxy_t *pptp;
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ipnat_t *ipn;
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ip_t *ip;
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int off;
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ip = fin->fin_ip;
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off = fin->fin_hlen + sizeof(udphdr_t);
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if (nat_outlookup(fin, 0, IPPROTO_GRE, nat->nat_inip,
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ip->ip_dst) != NULL) {
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if (ippr_pptp_debug > 0)
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printf("ippr_pptp_new: GRE session already exists\n");
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return -1;
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}
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aps->aps_psiz = sizeof(*pptp);
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KMALLOCS(aps->aps_data, pptp_pxy_t *, sizeof(*pptp));
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if (aps->aps_data == NULL) {
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if (ippr_pptp_debug > 0)
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printf("ippr_pptp_new: malloc for aps_data failed\n");
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return -1;
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}
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/*
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* Create NAT rule against which the tunnel/transport mapping is
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* created. This is required because the current NAT rule does not
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* describe GRE but TCP instead.
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*/
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pptp = aps->aps_data;
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bzero((char *)pptp, sizeof(*pptp));
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ipn = &pptp->pptp_rule;
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ipn->in_ifps[0] = fin->fin_ifp;
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ipn->in_apr = NULL;
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ipn->in_use = 1;
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ipn->in_hits = 1;
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ipn->in_ippip = 1;
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if (nat->nat_dir == NAT_OUTBOUND) {
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ipn->in_nip = ntohl(nat->nat_outip.s_addr);
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ipn->in_outip = fin->fin_saddr;
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ipn->in_redir = NAT_MAP;
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} else if (nat->nat_dir == NAT_INBOUND) {
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ipn->in_nip = 0;
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ipn->in_outip = nat->nat_outip.s_addr;
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ipn->in_redir = NAT_REDIRECT;
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}
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ipn->in_inip = nat->nat_inip.s_addr;
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ipn->in_inmsk = 0xffffffff;
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ipn->in_outmsk = 0xffffffff;
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ipn->in_srcip = fin->fin_saddr;
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ipn->in_srcmsk = 0xffffffff;
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bcopy(nat->nat_ptr->in_ifnames[0], ipn->in_ifnames[0],
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sizeof(ipn->in_ifnames[0]));
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ipn->in_p = IPPROTO_GRE;
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pptp->pptp_side[0].pptps_wptr = pptp->pptp_side[0].pptps_buffer;
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pptp->pptp_side[1].pptps_wptr = pptp->pptp_side[1].pptps_buffer;
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return 0;
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}
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void ippr_pptp_donatstate(fin, nat, pptp)
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fr_info_t *fin;
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nat_t *nat;
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pptp_pxy_t *pptp;
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{
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fr_info_t fi;
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grehdr_t gre;
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nat_t *nat2;
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u_char p;
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ip_t *ip;
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ip = fin->fin_ip;
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p = ip->ip_p;
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nat2 = pptp->pptp_nat;
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if ((nat2 == NULL) || (pptp->pptp_state == NULL)) {
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bcopy((char *)fin, (char *)&fi, sizeof(fi));
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bzero((char *)&gre, sizeof(gre));
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fi.fin_state = NULL;
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fi.fin_nat = NULL;
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fi.fin_fi.fi_p = IPPROTO_GRE;
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fi.fin_fr = &pptpfr;
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if ((nat->nat_dir == NAT_OUTBOUND && fin->fin_out) ||
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(nat->nat_dir == NAT_INBOUND && !fin->fin_out)) {
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fi.fin_data[0] = pptp->pptp_call[0];
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fi.fin_data[1] = pptp->pptp_call[1];
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} else {
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fi.fin_data[0] = pptp->pptp_call[1];
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fi.fin_data[1] = pptp->pptp_call[0];
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}
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ip = fin->fin_ip;
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ip->ip_p = IPPROTO_GRE;
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fi.fin_flx &= ~(FI_TCPUDP|FI_STATE|FI_FRAG);
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fi.fin_flx |= FI_IGNORE;
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fi.fin_dp = &gre;
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gre.gr_flags = htons(1 << 13);
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if (fin->fin_out && nat->nat_dir == NAT_INBOUND) {
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fi.fin_fi.fi_saddr = fin->fin_fi.fi_daddr;
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fi.fin_fi.fi_daddr = nat->nat_outip.s_addr;
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} else if (!fin->fin_out && nat->nat_dir == NAT_OUTBOUND) {
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fi.fin_fi.fi_saddr = nat->nat_inip.s_addr;
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fi.fin_fi.fi_daddr = fin->fin_fi.fi_saddr;
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}
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}
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/*
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* Update NAT timeout/create NAT if missing.
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*/
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if (nat2 != NULL)
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fr_queueback(&nat2->nat_tqe);
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else {
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nat2 = nat_new(&fi, &pptp->pptp_rule, &pptp->pptp_nat,
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NAT_SLAVE, nat->nat_dir);
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pptp->pptp_nat = nat2;
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if (nat2 != NULL) {
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(void) nat_proto(&fi, nat2, 0);
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nat_update(&fi, nat2, nat2->nat_ptr);
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}
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}
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READ_ENTER(&ipf_state);
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if (pptp->pptp_state != NULL) {
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fr_queueback(&pptp->pptp_state->is_sti);
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RWLOCK_EXIT(&ipf_state);
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} else {
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RWLOCK_EXIT(&ipf_state);
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if (nat->nat_dir == NAT_INBOUND)
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fi.fin_fi.fi_daddr = nat2->nat_inip.s_addr;
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else
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fi.fin_fi.fi_saddr = nat2->nat_inip.s_addr;
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fi.fin_ifp = NULL;
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pptp->pptp_state = fr_addstate(&fi, &pptp->pptp_state,
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0);
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if (fi.fin_state != NULL)
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fr_statederef(&fi, (ipstate_t **)&fi.fin_state);
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}
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ip->ip_p = p;
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return;
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}
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/*
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* Try and build up the next PPTP message in the TCP stream and if we can
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* build it up completely (fits in our buffer) then pass it off to the message
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* parsing function.
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*/
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int ippr_pptp_nextmessage(fin, nat, pptp, rev)
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fr_info_t *fin;
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nat_t *nat;
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pptp_pxy_t *pptp;
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int rev;
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{
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static char *funcname = "ippr_pptp_nextmessage";
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pptp_side_t *pptps;
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u_32_t start, end;
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pptp_hdr_t *hdr;
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tcphdr_t *tcp;
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int dlen, off;
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u_short len;
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char *msg;
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tcp = fin->fin_dp;
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dlen = fin->fin_dlen - (TCP_OFF(tcp) << 2);
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start = ntohl(tcp->th_seq);
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pptps = &pptp->pptp_side[rev];
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off = (char *)tcp - (char *)fin->fin_ip + (TCP_OFF(tcp) << 2) +
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fin->fin_ipoff;
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if (dlen <= 0)
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return 0;
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/*
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* If the complete data packet is before what we expect to see
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* "next", just ignore it as the chances are we've already seen it.
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* The next if statement following this one really just causes packets
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* ahead of what we've seen to be dropped, implying that something in
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* the middle went missing and we want to see that first.
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*/
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end = start + dlen;
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if (pptps->pptps_next > end && pptps->pptps_next > start)
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return 0;
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if (pptps->pptps_next != start) {
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if (ippr_pptp_debug > 5)
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printf("%s: next (%x) != start (%x)\n", funcname,
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pptps->pptps_next, start);
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return -1;
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}
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msg = (char *)fin->fin_dp + (TCP_OFF(tcp) << 2);
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while (dlen > 0) {
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off += pptps->pptps_bytes;
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if (pptps->pptps_gothdr == 0) {
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/*
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* PPTP has an 8 byte header that inclues the cookie.
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* The start of every message should include one and
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* it should match 1a2b3c4d. Byte order is ignored,
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* deliberately, when printing out the error.
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*/
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len = MIN(8 - pptps->pptps_bytes, dlen);
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COPYDATA(fin->fin_m, off, len, pptps->pptps_wptr);
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pptps->pptps_bytes += len;
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pptps->pptps_wptr += len;
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hdr = (pptp_hdr_t *)pptps->pptps_buffer;
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if (pptps->pptps_bytes == 8) {
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pptps->pptps_next += 8;
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if (ntohl(hdr->pptph_cookie) != 0x1a2b3c4d) {
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if (ippr_pptp_debug > 1)
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printf("%s: bad cookie (%x)\n",
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funcname,
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hdr->pptph_cookie);
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return -1;
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}
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}
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dlen -= len;
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msg += len;
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off += len;
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pptps->pptps_gothdr = 1;
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len = ntohs(hdr->pptph_len);
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pptps->pptps_len = len;
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pptps->pptps_nexthdr += len;
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/*
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* If a message is too big for the buffer, just set
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* the fields for the next message to come along.
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* The messages defined in RFC 2637 will not exceed
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* 512 bytes (in total length) so this is likely a
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* bad data packet, anyway.
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*/
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if (len > sizeof(pptps->pptps_buffer)) {
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if (ippr_pptp_debug > 3)
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printf("%s: message too big (%d)\n",
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funcname, len);
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pptps->pptps_next = pptps->pptps_nexthdr;
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pptps->pptps_wptr = pptps->pptps_buffer;
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pptps->pptps_gothdr = 0;
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pptps->pptps_bytes = 0;
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pptps->pptps_len = 0;
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break;
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}
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}
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len = MIN(pptps->pptps_len - pptps->pptps_bytes, dlen);
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COPYDATA(fin->fin_m, off, len, pptps->pptps_wptr);
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pptps->pptps_bytes += len;
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pptps->pptps_wptr += len;
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pptps->pptps_next += len;
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if (pptps->pptps_len > pptps->pptps_bytes)
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break;
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ippr_pptp_message(fin, nat, pptp, pptps);
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pptps->pptps_wptr = pptps->pptps_buffer;
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pptps->pptps_gothdr = 0;
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pptps->pptps_bytes = 0;
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pptps->pptps_len = 0;
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start += len;
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msg += len;
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dlen -= len;
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}
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return 0;
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}
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/*
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* handle a complete PPTP message
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*/
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int ippr_pptp_message(fin, nat, pptp, pptps)
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fr_info_t *fin;
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nat_t *nat;
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pptp_pxy_t *pptp;
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pptp_side_t *pptps;
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{
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pptp_hdr_t *hdr = (pptp_hdr_t *)pptps->pptps_buffer;
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switch (ntohs(hdr->pptph_type))
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{
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case PPTP_MSGTYPE_CTL :
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ippr_pptp_mctl(fin, nat, pptp, pptps);
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break;
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default :
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break;
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}
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return 0;
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}
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/*
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* handle a complete PPTP control message
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*/
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int ippr_pptp_mctl(fin, nat, pptp, pptps)
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fr_info_t *fin;
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nat_t *nat;
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pptp_pxy_t *pptp;
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pptp_side_t *pptps;
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{
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u_short *buffer = (u_short *)(pptps->pptps_buffer);
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pptp_side_t *pptpo;
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if (pptps == &pptp->pptp_side[0])
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pptpo = &pptp->pptp_side[1];
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else
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pptpo = &pptp->pptp_side[0];
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/*
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* Breakout to handle all the various messages. Most are just state
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* transition.
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*/
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switch (ntohs(buffer[4]))
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{
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case PPTP_MTCTL_STARTREQ :
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pptps->pptps_state = PPTP_MTCTL_STARTREQ;
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break;
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case PPTP_MTCTL_STARTREP :
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if (pptpo->pptps_state == PPTP_MTCTL_STARTREQ)
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pptps->pptps_state = PPTP_MTCTL_STARTREP;
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break;
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case PPTP_MTCTL_STOPREQ :
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pptps->pptps_state = PPTP_MTCTL_STOPREQ;
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break;
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case PPTP_MTCTL_STOPREP :
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if (pptpo->pptps_state == PPTP_MTCTL_STOPREQ)
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pptps->pptps_state = PPTP_MTCTL_STOPREP;
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break;
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case PPTP_MTCTL_ECHOREQ :
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pptps->pptps_state = PPTP_MTCTL_ECHOREQ;
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break;
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case PPTP_MTCTL_ECHOREP :
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if (pptpo->pptps_state == PPTP_MTCTL_ECHOREQ)
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pptps->pptps_state = PPTP_MTCTL_ECHOREP;
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break;
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case PPTP_MTCTL_OUTREQ :
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pptps->pptps_state = PPTP_MTCTL_OUTREQ;
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break;
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case PPTP_MTCTL_OUTREP :
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if (pptpo->pptps_state == PPTP_MTCTL_OUTREQ) {
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pptps->pptps_state = PPTP_MTCTL_OUTREP;
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pptp->pptp_call[0] = buffer[7];
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pptp->pptp_call[1] = buffer[6];
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ippr_pptp_donatstate(fin, nat, pptp);
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}
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break;
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case PPTP_MTCTL_INREQ :
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pptps->pptps_state = PPTP_MTCTL_INREQ;
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break;
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case PPTP_MTCTL_INREP :
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if (pptpo->pptps_state == PPTP_MTCTL_INREQ) {
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pptps->pptps_state = PPTP_MTCTL_INREP;
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pptp->pptp_call[0] = buffer[7];
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pptp->pptp_call[1] = buffer[6];
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ippr_pptp_donatstate(fin, nat, pptp);
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}
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break;
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case PPTP_MTCTL_INCONNECT :
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pptps->pptps_state = PPTP_MTCTL_INCONNECT;
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break;
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case PPTP_MTCTL_CLEAR :
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pptps->pptps_state = PPTP_MTCTL_CLEAR;
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break;
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case PPTP_MTCTL_DISCONNECT :
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pptps->pptps_state = PPTP_MTCTL_DISCONNECT;
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break;
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case PPTP_MTCTL_WANERROR :
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pptps->pptps_state = PPTP_MTCTL_WANERROR;
|
|
break;
|
|
case PPTP_MTCTL_LINKINFO :
|
|
pptps->pptps_state = PPTP_MTCTL_LINKINFO;
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
* For outgoing PPTP packets. refresh timeouts for NAT & state entries, if
|
|
* we can. If they have disappeared, recreate them.
|
|
*/
|
|
int ippr_pptp_inout(fin, aps, nat)
|
|
fr_info_t *fin;
|
|
ap_session_t *aps;
|
|
nat_t *nat;
|
|
{
|
|
pptp_pxy_t *pptp;
|
|
tcphdr_t *tcp;
|
|
int rev;
|
|
|
|
if ((fin->fin_out == 1) && (nat->nat_dir == NAT_INBOUND))
|
|
rev = 1;
|
|
else if ((fin->fin_out == 0) && (nat->nat_dir == NAT_OUTBOUND))
|
|
rev = 1;
|
|
else
|
|
rev = 0;
|
|
|
|
tcp = (tcphdr_t *)fin->fin_dp;
|
|
if ((tcp->th_flags & TH_OPENING) == TH_OPENING) {
|
|
pptp = (pptp_pxy_t *)aps->aps_data;
|
|
pptp->pptp_side[1 - rev].pptps_next = ntohl(tcp->th_ack);
|
|
pptp->pptp_side[1 - rev].pptps_nexthdr = ntohl(tcp->th_ack);
|
|
pptp->pptp_side[rev].pptps_next = ntohl(tcp->th_seq) + 1;
|
|
pptp->pptp_side[rev].pptps_nexthdr = ntohl(tcp->th_seq) + 1;
|
|
}
|
|
return ippr_pptp_nextmessage(fin, nat, (pptp_pxy_t *)aps->aps_data,
|
|
rev);
|
|
}
|
|
|
|
|
|
/*
|
|
* clean up after ourselves.
|
|
*/
|
|
void ippr_pptp_del(aps)
|
|
ap_session_t *aps;
|
|
{
|
|
pptp_pxy_t *pptp;
|
|
|
|
pptp = aps->aps_data;
|
|
|
|
if (pptp != NULL) {
|
|
/*
|
|
* Don't bother changing any of the NAT structure details,
|
|
* *_del() is on a callback from aps_free(), from nat_delete()
|
|
*/
|
|
|
|
READ_ENTER(&ipf_state);
|
|
if (pptp->pptp_state != NULL) {
|
|
pptp->pptp_state->is_die = fr_ticks + 1;
|
|
pptp->pptp_state->is_me = NULL;
|
|
fr_queuefront(&pptp->pptp_state->is_sti);
|
|
}
|
|
RWLOCK_EXIT(&ipf_state);
|
|
|
|
pptp->pptp_state = NULL;
|
|
pptp->pptp_nat = NULL;
|
|
}
|
|
}
|